Antenna reel control



J1me 1943. N. M. RASKHODOFF ANTENNA REEL CONTROL Filed Sept. 16. 1941 4 9''. I. k v/ m /2 C A 2 M5 2 mM 40 (1 mm a MN n+ a w FTM N/cho/as M lQas/zodoff INVENTOR.

BY 2,416). at

ATTORNEY.

Patented June 8, 1943 UNITED STATES PATENT OFFICE ANTENNA REEL CONTROL.

Application September 16, 1941, Serial No. 410,971

5 Claims.

This invention relates to antenna reels and, more particularly, to the control of the length of wire released by an antenna reel.

Where communication with ground stations is desired, many modern aircraft are fitted with multiple channel radio transmitting and receiving equipment. On long flights, the transmission distances may become very great, and it is desired to attain the utmost in the efiiciency of the transmitting antenna of the aircraft be cause of the necessarily limited power output of aircraft transmitters.

It is well known that the efficiency of an antenna for the transmission of electromagnetic waves is largely determined by the dimensions of that antenna, and that the optimum dimensions for the antenna vary with the frequency of the energy to be transmitted. At the frequencies usually employed, the trailing wire type of antenna generally has the best radiation characteristic of any of the aircraft transmitting antennas. This type of antenna is adjusted to optimum dimensions by varying its length. Obviously, if a number of widely separated transmission frequencies are to be radiated, it is desirable to use a number of different lengths of trailing wire antenna, perhaps one for each frequency.

Up to the present time it has been necessary for the operator to adjust the length of the trailing wire antenna as a separate operation, which adds to the burden of his already numerous duties.

One of the principal objects of this invention is to provide a novel antenna reel control whereby predetermined lengths of antenna may be readily extended.

Another object of this invention is to provide a novel antenna reel control operated by the bandswitch of a multi-band radio apparatus to extend predetermined lengths of antenna.

Still another object of this invention is to reduce the number of operations required in adjusting radio transmitting equipment for optimum efficiency.

Other objects and advantages will in part be disclosed and in part be obvious when the following specification is read in conjunction with the drawing in which:

Figure 1 is a combined schematic and diagrammatic representation of one form of my inven tion.

It is to be understood that this drawing is intended to illustrate a preferred form of the invention, and is not to comprise a limitation in the content or scope of the invention.

Referring in greater detail to Figure 1, the weight I is connected to the free end of the antenna wire 2. The other end of the antenna wire 2 is secured to the reel 3 which is rigidly attached to the worm gear 4 and is rotated thereby upon operation of the reversible series wound motor 5, with the attached shaft 6 and worm l. The reel 3 may be constructed of a material having good conductivity and be insulated from the framework of the machine by the use of insulating material in the structure of Worm gear 4, and by mounting the reel on a shaft 8 which is also made of insulating material. External connection to the reel is obtained by mounting the slip ring 9 on the same shaft as the reel, electrically connecting this slip ring to the reel and maintaining a stationary brush I0 in contact with the slip ring 9. The brush I0 may be connected to the antenna terminal ll of a suitable radio transmitter l2 via the lead 13. A footage indicating dial it may be driven from the worm gear 4 through the reduction gearing IS. The footage indicating dial, cooperating with the stationary index it, indicates the length of antenna lead extended. All the above parts are already known in combination, and together they constitute a Well known type of antenna reel installation.

The shaft I! is firmly attached to the footage indicating dial and to a suitable preselector device such as the split disc controller assembly comprising the two arcuately formed conducting sectors 18, i9 insulated from the shaft I! by the annularly shaped ring 20 of dielectric material and from each other by the air gaps 23. In this manner, movement of the dial H is directly transmitted to the split disc controller assembly. Contacts 2| are adapted to engage the conducting sectors 18, I9 and are themselves connected to the contacts of selector switch 22 as shown. The construction of the apparatus is preferably such that any contact 2| may be adjusted to lie over an air gap when the split disc controller reaches a predetermined angular position, but it may be desirable to limit all adjustment of contacts to lie within a particular are of 180 degrees or less. The wiper arm of selector switch 22 may be mechanically coupled to a band switch shaft extension 24 from the transmitter l2 and is electrically connected to the negative terminal of the battery 25, which may be the source of power for energizing the motor 5.

In the motor 5, the brushes 21, 28 contact the commutator 26, brush 2'! being externally connected to the positive terminal of battery 25, while brush 28 is connected to the junction of the clockwise fieldwinding 29 and the counter-clockwise field winding via lead 3|. Clockwise field winding 29 may be connected to the sector I!) in any suitable manner, represented in the drawing by lead 32. In like manner the counterclockwise field winding 30 may be connected to the conducting sector IB by the lead 33 or its equivalent.

Disabling relay 34 may be connected across the armature of the motor 5 as shown in the drawing. This relay is provided with the normally closed contacts 35 which are connected in series with the transmitter anode supply and serve to interrupt this circuit while the antenna reel is in operation.

In the drawing I have shown the selector switch 22 adjusted to pay out an additional length of antenna. The operation of the apparatus is as follows: the battery circuit through the armature of motor 5, and through the clockwise field 29 is completed through the conducting sector 19, contact 21a and through the contact and wiper arm of selector switch 22. The current flowing through this circuit operates the motor and drives the reel 3 clockwise, releasing an additional length 'of wire. The split disc controller is also driven clockwise through gear train l5, footage indicating dial l4 and shaft ll. When the air gap 23 reaches the contact 2la the electric circuit through the motor and battery is opened,

and the reel with its associated elements coasts 1 to a stop. If the reel coasts an amount greater than that corresponding to the width of air gap 23, contact 2la engages conducting sector I8 of the split disc controller exciting the counterclockwise field 30, thereby returning the air gap to the position under contact 2la and indexing the split disc to the predetermined angular position corresponding to the desired length of antenna wire;

During the operation of motor 5, the voltage across the armature energizes the disabling relay 34, opening contacts 35 and interrupting the high voltage supply to the anodes of the transmitting tubes. This prevents possible damage to the elements of the transmitter while theantenna wire is of such length as to present an unfavorable load to'the output circuits. After proper indexing of the split disc controller, the power supply circuit to the motor 5 is broken and the voltage across the armature drops to zero, de-energizing i relay 34 and restoring the high voltage supply to the transmitter anode circuits.

Setting the bandswitch of transmitter l 2 to another band will bring into play another of the contacts 2 I through the action of selector switch 22. In the same manner as described above, the antenna reel will now be actuated to extend or retract the antenna wire to that value of length satisfying the angular position of the active contact 2|. I i

As a part of the normal tune-up procedure which is a part of the installation of a transmitter in an aircraft, the trailing wire antenna may be adjusted to the value found to be the best for operation on a given channel and the appropriate contact 2! so stthat when the transmitter is switched to this channel, this selected length will be automatically paid out. In using apparatus incorporating my invention, therefore, the operator need adjust only one control in selectin both the channel and the proper antenna length for operation on that channel.

For the sake of simplicity, I have shown the selector switch 22 operated by a bandswitch shaft extension from the transmitter I2, however, it is understood that in a preferable form of the invention, the selector switch 22 might be constructed as a part or section of the transmitter channel selector switch and located within the transmitter proper, the electrical connections being made by means of suitable cables. As a further alternative, the selector switch 22 might be disconnected completely from any link with the transmitter channel selector switch and the setting of the switch 22 manually made by the operator as a separate operation. Although this latter arrangement does not have the advantages of the combined transmission channelantenna length switch, it is still superior to present methods of adjustment which require the operators concentration on a revolution counter or antenna length indicator. As is readily seen, my invention may also be used in conjunction with any other radio apparatus, such as, for example, a receiver of any of the well known types.

It will be obvious that many changes and modifications may be made in the invention without departing from the spirit thereof as expressed in the foregoing description and in the appended claims:

I claim:

1. In combination with an antenna reel and radio apparatus having a channel selector switch, means for automatically extending a plurality of predetermined lengths of antenna wire in accordance with the setting of said channel selector switch, said means comprising, a reversible electric motor operably connected to said reel, a power source for said motor, a split disc controller for said electric motor, said split disc controller being operably connected to said reel, a plurality of stationary, contacts engaging said split disc controller, and means mechanically coupled to said channel selector switch for selectively energizing said contacts.

2. In combination with an antenna reel and radio apparatus having a channel selector switch, means for automatically extending a plurality of predetermined lengths of antenna wire in accordance with the setting of said channel selector switch, said means comprising a reversible electric motor operably connected to said reel, a power source for said motor, a split disc controller for said electric motor, said split disc controller bein operably connected to said reel, a plurality of stationary contacts engaging said split disc, said contacts being circumferentially adjustable around the periphery of said split disc, and means mechanically coupled to said channel selector switch for selectively energizing said contacts.

3. In combination with an antenna reel and radio apparatus having a channel selector switch, means for automatically extending a plurality of predetermined lengths of antenna wire in accordance with the setting of said channel selector switch, said means comprising; a reversible electric motor operably connected to said reel, a power source for said motor, a split disc controller for said electric motor, said split disc controller being operably connected to said reel, a plurality of stationary contacts engaging said split disc, said contacts being circumferentially adjustable around the periphery of said split disc, and means electrically connecting said contacts with a portion of the contacts of said channel selecto switch.

4. In combination with an antenna reel and radio apparatus having a channel selector switch,

.a motor operably connected to said reel, a pre selector device operably connected to said reel,

said preselector device having adjustable contacts, a source of electric power connected with said preselector device, means actuated in accordance with the setting of said channel selector switch to selectively energize said contacts, said preselector device and said motor co-operating to pay out a plurality 'of predetermined lengths of wire in accordance with the setting of said channel selector switch.

5. In combination with radio apparatus having 10 

